The benefits of proper inflation of aircraft tires are well known. For example, properly inflated aircraft tires protect against tire failure due to extreme deflection of the tires during take-off and landing, and also help to reduce dynamic stresses in the tires to thereby extend the working life of the tires.
It is well known to monitor the condition of a pneumatic tire using one or more sensors disposed within the tire or on a wheel rim upon which the tire is mounted. Conventional tire monitoring systems typically utilize radio frequency (RF) transponders that are provided with sensors for detecting various conditions of a tire, such as the internal pressure and temperature of the tire. The transponders may be active or passive. Active transponders have their own power supply (e.g., a battery), while passive transponders are powered by the energy of an incoming RF signal from a reader device, as known in the art. The transponder generates a signal to be received by the reader device and which includes information related to the sensed conditions of the tire.
Because RF transponders have a relatively limited communication range, reader devices must be located relatively close to the transponders to receive the signals. Conventional instrumented tires have utilized a transponder fixed to an interior surface of the tire, and an antenna which extends circumferentially around the tire to facilitate communication between the transponder and the reader device regardless of the angular orientation of the transponder in the rotating tire relative to the reader device. One drawback of using circumferentially extending antennas mounted within the interiors of pneumatic tires is that cyclic tensile and flexural loading of the tires as they rotate causes stress fractures in the antenna which may degrade performance and/or cause the antennas to break. The problem is compounded in pneumatic tires used in aircraft, which must not only handle heavy loads, but must also accommodate high forces when the tires impact the ground during landing maneuvers.
A need therefore exits for a system to monitor the conditions of aircraft tires that overcomes these and other drawbacks of the prior art.